Coal gasification

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COAL GASIFICATION - notes From SR we obtain syngas (CO+H2), how we can transform syngas into H2 fuel ? Downstream of SR we will have a series of WGS reactors that allow to exploit the residual content of steam in syngas to promote WGS reaction CO+H2O→CO2+H2 and further enrich the syngas in H2. WGS: mildly exothermic, favoured at low T thermodynamically, the kinetics of the reaction depends on the catalyst that we use. Two kind of catalyst are commercially used: • the older one is an iron-based catalyst, it is a high T catalyst (300-350°C, adiabatic reactor), from a thermodynamic point of view we are not able to achieve high conversion (60%); • after the development of copper containing catalyst we are able to operate at lower temperature: we have 2 stages of WGS operating at high T with iron-based catalyst (where most of conversion is achieved) and a following copper containing catalyst (we have 3 adiabatic reactors), which is active at a lower T than the other catalyst (250°C) WGS reaction is more thermodynamically favoured. Example: provide H2 to fuel cells in stationary applications (residential combine heat & power units) are composed by: a stage of SR; production of syngas; before entering in the fuel cell we need to abate the CO concentration because PEM (Pt) can stand a CO concentration of few ppm, we performed a deep purification of syngas by means of 2 stages of WGS at high T + additional purification step (selective CO oxidation catalyst, inject air that converts CO into CO2 which is harmless for the fuel cell without increasing the content of H2). Syngas conversion into methanol: methanol is a very important intermediate for industry of plastics, we are interested in methanol as a fuel or as a precursor of a fuel. From methanol: • methanol can be use as fuel…